The strongest punctuation mark is the period or “full stop” (which is perhaps on par with the exclamation mark and the question mark). The next is the semi-colon; and finally comes the comma. By ‘strong’ here we mean influence on the cadence of your reading, especially your pauses and intonation in oration. When do you use which one?

I’ve read classic books in which an author wrote very long paragraphs (sometimes running to a dozen lines or longer), broken into segments with just commas. Many equally masterful writers would throw several semi-colons into such passages, so as to group the segments into batches that seem to flow better. I have also read good writers who cut such passages into very short sentences with periods and periods and periods. It is to some extent a matter of your preferred style. What one should avoid is pouring on a glut of words without adequate punctuation except perhaps the occasional use of conjunctions (‘and,’ ‘but,’ ‘however,’ etc.). A reader tires of such writing, or begins to stumble, easily.

The Comma for Clarification
One magazine ad for a diabetes medicine was worded as follows: Diabetes destroys nerves which may cause pain.” A casual reading of that sentence could lead to a conclusion that is the direct opposite of what the ad intended. To understand the sentence we must determine the antecedent of “which.” (The antecedent of a word in a sentence is a preceding word or phrase to which it refers. If I say “I read a book and I enjoyed it,” the antecedent of “it” is “book.”)

So, in that ad, what is the antecedent of “which”? In other words, what is causing the pain? If nerves cause pain, then diabetes is doing a good deed by destroying them to stop pain! But we know that is not true: destruction of nerves is what causes pain. So, diabetes is doing a bad deed by destroying nerves and thus causing pain. What the advertisers meant to say is best rendered with a comma after “nerves.” (“Diabetes destroys nerves, which may cause pain” is the correct sentence.) Thus, a comma after “nerves” inverts the meaning of the sentence.

The stakes in the use of the comma can be much higher than mere nerve pain. Consider the serial comma. It is a comma in a special role: it comes before the final member in a list of denoted items. For instance, in the sentence, (1) “Divide a chocolate bar equally between Mary, Paul, and John” that last comma is the serial comma. Its use is seriously declining in the USA, and most writers now omit it altogether.

Suppose a zillionaire bequeaths his estate “to be divided equally between my three sons Tom, Dick and Harry.” It used to be argued that such a man was instigating a probate battle in his family because, if Tom retained a clever lawyer, he could obtain half of the state, leaving the other half to Dick and Harry. (That is equal division between two the parties delineated by the comma.) These days, however, each son might get a third of the estate, with or without a serial comma after Dick. But, yes, a fortune could depend on that second comma! Lawyers excel in tweaking out (and exploiting) minutiae like that. If you have a clever daughter and give her a chocolate bar to share equally with her brother and sister, be sure to use a serial comma!

The Hyphen
Take the hyphen, too, which is all but extinct now. It is hard to make any sense of the following sentence: “We buy demand and supply statistics to predict sales.” Now insert two hyphens (one on either side of the word “and”) and the meaning comes into focus.

The Parentheses
In an earlier essay on this site (The Period and he Parenthesis, May 2015) we saw that a pair of parentheses functions in such a manner that, if you threw away the pair and everything inside it, the sentence that remains would retain its integrity without needing any adjustment. That clarification resolved the question of whether a period should be placed before or after the closing parenthesis: A sentence that begins after the opening parentheses should end inside, with the period placed before the closing parenthesis; conversely, one that begins before the opening parenthesis should end outside, i.e. after the closing parenthesis.

Marks for “Heads-Up”
It is a pity that English does not employ an inverted question mark to start off a sentence that is in the interrogative mood as Spanish does (or an inverted exclamation mark for the imperative mood) to give the reader a ‘heads-up’ that what follows calls for an adjustment of intonation. I find I sometimes must get to the end of a long sentence before I realize I have read it with the wrong inflexion.

The colon ( : )
This punctuation mark serves so many different purposes in written English that it is hard to explain all of them exhaustively. As a good approximation, Wikipedia says the colon “is used to explain or start an enumeration” (of a category); it also has other uses, but let us concentrate on its main use (as stated by Wikipedia).

The colon is included here because of my experience with “experts” (editors & reviewers) who have stated rather incorrect or incomplete views on what must follow a colon. In its role of enumerating/elaborating examples, a colon may be followed by: a word, a phrase, a clause, a sentence, or a full paragraph. (Note the use of the colon in the preceding sentence.)

If what follows your colon is a list, it is less confusing if the items on that list are consistently in the same format — all of them being single words or phrases, or clauses, or sentences — (rather than mixtures of the different categories).

Bullets
The practice of delineating a list with “bullets” is relatively new (corresponding roughly with the emergence and supremacy of the PC as a tool for composition of writings); but it can be more tidy and helpful. As with a colon, it is useful to ensure that the items of individual bullets are in the same format. For instance, if the first bullet is a single word, subsequent bullets may be single words or short phases, but not complete sentences.

Beyond that, how to end the item on each bullet (with a comma, semi colon, or period) follows the normal rules of punctuation. If it is a sentence, it has to end with a period; if a word, with a comma; and if a phrase or a clause, with a semi colon — especially if that phrase/clause is long or complex enough to require other punctuation marks within it.

PUNCTUATING SENTENCES was last modified: September 13th, 2016 by Lyn Thomas-Ogbuji